Blocking Cell Plugging Color Hue Shift Color Too Strong Color Variation Color Weak Cylinder Wear Gloss (Too High Or Too Low) Inadequate Drying Ink Settling Mottling, Puddling, Volcanoes Picking Poor Trapping Poor Wipe Scuffing Scumming Skipping Strike-Through Whiskering Drying In Foaming Poor Ink Mileage Poor Printability
Blocking Symptom: The print side and unprinted side of the printed materials stick together when they are in contact in the roll. 1. Press conditions 2. Ink film too thick 3. Improper resin selection in the ink formula 4. Too much slow solvent being use to adjust viscosity of the ink 1. Increase oven temperatures. Make sure exhaust blowers are at maximum velocity; use spot air in heavily etched areas 2. Reduce viscosity of ink 3. Consult with ink manufacturer to reformulate with better solvent release or higher melting point resin 4. Review solvents being used for viscosity adjustments and get recommendation from ink supplier
Cell Plugging Symptom: Weak, non-uniform dots. Differs from drying in, as residue in cells does not resolubilize readily. 1. Cells plugged with paper, paper coating and ink 1. Check paper coating integrity against control paper Increase ink fountain temperature Maintain ink fountain temperature above dew point at all times
Color Hue Shift Symptom: Movement within register causes changes in shade to occur. Predominantly seen in light tone areas. 1. Improper cell configurations on cylinders 2. Electric eyes may be out of alignment 3. Dryers may be too hot, causing the web to shrink 4. Poor register 5. Ink viscosity may be too high 6. Too much slip compound in the ink 1. Check cell configuration; consult cylinder department 2. Adjust the electric eyes 3. Adjust heat level in dryers 4. Consult cylinder department 5. Lower ink viscosity by adding solvent 6. Add less slip compound to the ink or add fresh ink to fountain; consult ink manufacturer
Color Too Strong Symptom: Visual color different from standard. 1. Cell volume too great 2. Inappropriate cylinder etch or engraving 3. Nonabsorbent stock 4. Ink viscosity too high 5. Ink pigmentation too strong 1. Lacquer in part of the cylinder to reduce cell volume 2. Consult cylinder department 3. Add solvent to reduce ink viscosity 4. Add solvent to reduce ink viscosity 5. Add clear extender
Color Variation Symptom: Inconsistent color reproduction. 1. Lack of viscosity control 2. Automatic inker not adjusted; solvent, ink and varnish flowing in at random, unequal rates 3. Inconsistent operator procedures 4. Variation in type and condition of equipment: cylinders, impression rollers, doctor blades 5. Changes in paper 6. Variations in ink batches 1. Establish one set of procedures for all operators; add only measured amounts of solvent to reduce ink to proper running viscosity 2. Check flow rates and equalize; calibrate flow rates 3. Establish one set of procedures 4. Eliminate or reduce variations in equipment between presses; clean cylinders, rollers, doctor blades; check durometer, reading of impression rollers; replace if necessary; adjust viscosity for each print unit 5. Adjust ink viscosity to compensate for change, if possible; consult ink manufacturer for additional assistance 6. Inks may vary in strength; consult ink manufacturer
Color Weak Symptom: Visual color different from standard. 1. Worn cylinder 2. Too much solvent added when ink was reduced to press viscosity 3. Excess clean-up solvent in the system 4. Cylinder dirty encrusted with ink 5. Doctor blade angle set incorrectly 6. Impression roller durometer too high 7. Very absorbent paper stock 8. Ink pigmentation weak 9. Over extended, i.e. too much extender on press 1. Consult cylinder department; re-etch cylinder to increase cell volume. Decrease extender cuts; add toner if needed 2. Replace ink or add fresh ink to increase viscosity 3. Replace ink or add fresh ink to increase viscosity 4. Clean cylinder with brush and solvent to remove dried ink from cells; use brass bristle brush for chrome 5. Flatten angle to apply more ink 6. Consult roller manufacturer and replace if necessary 7. Run a higher viscosity, stronger ink and/or less extender in fountain 8. Add toners to ink or decrease extender cuts 9. Check auto ink batcher
Cylinder Wear Symptom: Abrasive damage to the chrome surface of the cylinder. 1. Bad chrome 2. Foreign particles lodged behind the doctor blade 3. Irregular cylinder surface 4. Parting shell 5. Doctor blade 6. Ink drying too fast 7. Ink abrasiveness 8. Paper or paper coating abrasiveness 1. Check thickness, plating, hardness, smoothness and ductility of chrome plating 2. Filter ink with at least a 25-micron filtering device and/or remove ink, adding fresh ink 3. Polish surface; re-cut and re-chrome cylinder; consult cylinder department 4. Have a new cylinder made; consult cylinder department 5. Check doctor blade pressure; check blade and angle for any unusual wear 6. Reduce drying rate of ink (See "Drying in") 7. Have supplier re-check all raw materials in formula for abrasiveness 8. Check for contamination in fountain (paper coating, sludge, etc.); consult with paper supplier about changing paper
Drying In Symptom: Symptom: Ink is drying in the cylinder cells. 1. Press conditions 1. Check air velocity and oven temperature Check angle of doctor blade Remove any spot air system that may be connected and causing drying-in Cool fountains Increase press speed Wipe or scrub cylinder 2. Ink drying too fast 2. Add slow drying solvent Vehicle system can be changed Decrease viscosity Advise ink supplier of this condition Use solvent with more solubility
Foaming Symptom: Frothing of the ink. 1. Ink falls excessive distance when recycled into container 2. Too much air is introduced into the ink 3. Air is not allowed to escape 4. Too much solvent added when ink was reduced to press viscosity 5. Improperly formulated ink 1. Eliminate long fall by using hose or pipe to introduce ink into pan 2. Check for and repair leaky pump; adjust pump speed to reduce agitation. Maintain ink level well above pump intake 3. Add solvent to ink to lower viscosity 4. Add fresh ink to increase viscosity 5. Add defoamer compound to ink; consult ink manufacturer
Gloss (Too High or Too Low) Symptom: Improper reflective properties of the printed ink. 1. Too high gloss 1. Reduce viscosity by adding solvent Use a pigmented extender 2. Too low gloss 2. Add gloss extender, such as liquid resin or extender varnish Increase viscosity by lowering the amount of solvent added to the virgin ink Change reducing solvent to lower dilution ratio Call ink manufacturer
Inadequate Drying Symptom: Ink film remains wet or tacky to the touch. 1. Dryer temperature too low for speed of web 2. Ink film does not dry at correct rate 3. Reducing solvent used has too slow drying rate 4. Poor solvent release properties of ink 1. Increase dryer temperature to specification level; reduce web speed 2. Adjust press speed and/or ink viscosity; consult with ink manufacturer 3. Use faster drying solvent such as fast drying acetates; avoid build-up of slow drying solvent 4. Consult with ink manufacturer to reformulate in alternate vehicle
Ink Settling Symptom: Separation of pigments. 1. Pump velocity in sump too low 2. Build-up in ink fountain 3. Previously used ink which has low viscosity 4. Old ink 5. Improper ink formulation 1. Check paper; replace if necessary Adjust viscosity 2. Increase circulation by adding drains or additional piping 3. Mix with fresh ink and use 4. Rotate inventory 5. Consult ink manufacturer
Mottling, Puddling, Volcanoes Symptom: Random light and dark areas that give the printed area an uneven appearance. 1. Non-uniform paper surface 2. Pattern in cylinder due to large cells 3. Improper pressure settings on impression roller 4. Ink film too thin 5. Ink improperly formulated 1. Adjust viscosity 2. Consult with cylinder department 3. Adjust impression roller 4. Replace ink or add fresh ink to increase viscosity (See "Color Weak") 5. Consult ink manufacturer
Picking Symptom: Removal of part of paper surface or underlying ink film. 1. Press conditions 2. Ink properties 3. Paper properties 1. Make sure ink fountain temperature is above dew point Reduce press speed Reduce impression roller pressure Make sure exhaust blowers are at maximum velocity Use spot air in heavily etched areas 2. Adjust ink viscosities Add a faster drying solvent Change ink system for better solvent release 3. Check surface strength of stock Consult with paper supplier
Poor Ink Mileage Symptom: Excessive ink used per ton of paper stock. 1. Excessive waste on start-up 2. Paper stock too absorbent 3. Improper ink and solvent blend 4. Ink penetrating into stock too fast 5. Different specific gravities of inks 1. Improve start-up procedure 2. If possible, change to a less absorbent paper (See "Strike Through") 3. Adjust to proper ink and solvent ratio to obtain prescribed viscosity 4. Consult with ink manufacturer to reformulate ink with more holdout 5. Consult your ink manufacturer for specific gravity values of inks
Poor Printability Symptom: Lack of print quality due to various factors in the printing process. 1. Press conditions 2. Paper properties 3. Ink properties 1. Check press speed Check oven temperature Check exhaust fans and spot air Check ESA rollers Check doctor blade and cylinder for wear Check impression roller pressure 2. Check for flaws in paper coating Check for holes, slugs, or wrinkles Check paper surface characteristics 3. Change solvency Reduce ink viscosity with normal thinner Reduce ink with higher boiling solvent or blend
Poor Trapping Symptom: Succeeding layers of ink do not lay down properly. 1. Ink viscosity too high 2. Base ink still wet 3. Underlying film being resoftened due to high acetate content of diluting solvent 4. Underlying ink contains excessive wax compound 5. Silicones or slip compounds in underlying ink. 1. Reduce ink viscosity 2. Adjust air velocity of drying condition around images Remove extra solvents Increase oven temperature and air velocity Increase ink drying speed with fastdrying solvent 3. Blend in alcohol to reduce acetate content of ink being trapped 4. Add pigmented extender Reduce wax compound Add fresh ink 5. Have ink supplier remove silicone from ink
Poor Wipe Symptom: Ink is not being removed from non-etched areas of the cylinder. 1. Press conditions 2. Ink properties 1. Check doctor blade for nicks, flaws or excessive wear; rehone or replace if necessary Check angle of doctor blade; adjust if necessary Remove dirt or foreign matter from under doctor blade Check railroads due to scratches in cylinder Increase drying rate of ink; blow air between nip and blade If scum occurs, polish cylinder and speed up drying rate 2. Ink too highly pigmented: add clear extender varnish Ink drying too fast or slow: slow down or speed up as required with the solvents recommended by your ink supplier Ink viscosity too high or low: adjust to prescribed viscosity
Scuffing Symptom: Scratches in printed ink film due to poor rub resistance when abraded. 1. Press conditions 2. Ink properties 3. Paper properties 1. Increase oven temperature or CFM Adjust folder to improve slip 2. Add hardeners or wax compounds to ink Check ink viscosity; if low, adjust upwards Change ink system's solvent release to upgrade ink film integrity Notify ink supplier 3. Check abrasion of current stock versus standard; consult paper supplier
Scumming Symptom: Ink deposits on the non-etched areas of the gravure cylinder. 1. Doctor blade variables 2. Ink viscosity too high 3. Ink drying rate too slow on paper 4. Ink drying too slowly on cylinder 5. Cylinder surface too smooth 6. Ink formulation out of balance 1. Improve blade edge finish; sharpen blade contact angle; decrease blade thickness; increase blade pressure; ensure blade is parallel along length of cylinder 2. Reduce ink with the recommended solvent 3. Increase drying rate with faster drying solvent 4. Introduce local air drying; adjust point of wipe further away from point of impression to allow ink film to dry before transferring to web 5. Send cylinder to cylinder department for rechroming and polishing 6. Consult with ink manufacturer
Skipping Symptom: Cells fail to print out, causing speckles in printed materials. 1. Rough paper 2. Cylinder conditions 3. Ink viscosity too high 4. Drying rate too fast (drying in cells) 5. Improperly formulated ink 1. Increase impression roller pressure; change to harder durometer roller Make sure ESA is on and at the proper polarity setting Change ESA roller Change paper 2. Check screen angle Check chrome Check cell configuration 3. Check viscosity; reduce to correct level by adding measured amount of solvent 4. Increase press speed to reduce fountain temperature; consult with ink manufacturer to reformulate using solvents with lower evaporation rates 5. Consult ink manufacturer
Strike-through Symptom: Excessive ink absorbing into paper stock and appearing on reverse side. 1. Cylinder etch too deep 2. Paper too absorbent 3. Change in basis weight of paper 4. Insufficient ink holdout 1. Lacquer cylinder Add pigmented extender Increase ink viscosity Increase oven temperature and air velocity 2. If possible, change to a less absorbent paper or increase ink viscosity 3. Revert to original basis weight 4. Consult with ink manufacturer to reformulate ink for more holdout
Whiskering Symptom: Hairy edges of printed areas. 1. Paper properties 2. Press conditions 3. Ink properties 1. Remove static from web with tinsel, humidity or other static eliminators 2. Change conductivity of impression roller Decrease cylinder cell volume Decrease doctor blade pressure Reverse polarity of ESA unit Reduce press speeds Extend oven hood close to nip 3. Increase ink viscosity Steam web before and after problem unit